Summary of Significant Accounting Policies - Credit Line (Details) (Wells Fargo, USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 12, 2011
Debt Instrument [Line Items]
Applicable interest rate		2.50%
Description of interest rate spread	above one or three month LIBOR
Minimum amount required to keep in bank account		$ 5,000,000
Letter of credit outstanding	100,000
Revolving Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing capacity of credit facility		5,000,000
Revolving Credit Facility | Letter of Credit
Debt Instrument [Line Items]
Borrowing capacity of credit facility		$ 2,000,000